#include <algorithm>
#include <iostream>
#include <map>
#include <string>
#include <type_traits>
using namespace std;

// 比较器升序 < 换成 > 就是降序排列了
struct student {
  int age;
  int id;
  std::string namefirst;
  std::string namelast;
  bool operator<(const student &p) {
    if (id != p.id) {
      return id < p.id;
    }
    if (age != p.age) {
      return age < p.age;
    }
    if (namefirst != p.namefirst) {
      return namefirst < p.namefirst;
    }
    if (namelast != p.namelast) {
      return namelast < p.namelast;
    }
    return false;
  }
};

int main() {}
